Index for Section 3

Alphabetical listing for P

Bottom of page

pthread_setschedparam(3)
NAME
  pthread_setschedparam - Changes a thread's scheduling policy and scheduling
  parameters.

LIBRARY
  DECthreads POSIX 1003.1c Library (libpthread.so)

SYNOPSIS
  #include <pthread.h>

  int  pthread_setschedparam(
		     pthread_t			thread,
		     int			policy,
		     const struct sched_param	*param);

STANDARDS
  interfaces documented on this reference page conform to industry standards
  as follows:

  IEEE Std 1003.1c-1995, POSIX System Application Program Interface

PARAMETERS
  thread    Thread whose scheduling policy and parameters are to be changed.

  policy    New scheduling policy value for the thread specified in thread.
	    The following are valid values:

	      ·
	      SCHED_BG_NP

	      ·
	      SCHED_FG_NP

	      ·
	      SCHED_FIFO

	      ·
	      SCHED_OTHER

	      ·
	      SCHED_RR
  See Guide to DECthreads for a description of the scheduling policies.

  param	    New values of the scheduling parameters associated with the
	    scheduling policy for the thread specified in thread.  Valid
	    values for the sched_priority field of a sched_param structure
	    depend on the chosen scheduling policy. Use the POSIX routines
	    sched_get_priority_min(3) or sched_get_priority_max(3) to
	    determine the low and high limits of each policy. Additionally,
	    DECthreads provides nonportable priority range constants, as
	    follows:

	      ·
	      PRI_FIFO_MIN (low) to PRI_FIFO_MAX (high)

	      ·
	      PRI_RR_MIN (low) to PRI_RR_MAX (high)

	      ·
	      PRI_OTHER_MIN (low) to PRI_OTHER_MAX (high)

	      ·
	      PRI_FG_MIN_NP (low) to PRI_FG_MAX_NP (high)

	      ·
	      PRI_BG_MIN_NP (low) to PRI_BG_MAX_NP (high)
  The default priority varies by DECthreads platform.  On Tru64 UNIX, the
  default is 19 (that is, the POSIX priority of a normal timeshare process).
  On the non-UNIX platforms, the default priority is the midpoint between
  PRI_FG_MIN_NP and PRI_FG_MAX_NP.

DESCRIPTION
  This routine changes both the current scheduling policy and associated
  scheduling parameters of the thread specified by thread to the policy and
  associated parameters provided in policy and param, respectively.

  All currently implemented DECthreads scheduling policies have one
  scheduling parameter called sched_priority.  For the policy you choose, you
  must specify an appropriate value in the sched_priority field of the
  sched_param structure.

  Changing the scheduling policy or priority, or both, of a thread can cause
  it to start executing or to be preempted by another thread.  A thread
  changes its own scheduling policy and priority by using the handle returned
  by the pthread_self(3) routine.

  This routine differs from pthread_attr_setschedpolicy(3) and
  pthread_attr_setschedparam(3), in that those routines set the scheduling
  policy and parameter attributes that are used to establish the scheduling
  priority and scheduling policy of a new thread when it is created.
  However, this routine changes the scheduling policy and parameters of an
  existing thread.

RETURN VALUES
  If an error condition occurs, no scheduling policy or parameters are
  changed for the target thread, and this routine returns an integer value
  indicating the type of error.	 Possible return values are as follows:

  0	    Successful completion.

  [EINVAL]  The value specified by policy or param is invalid.

  [ENOTSUP] An attempt was made to set the scheduling policy or a parameter
	    to an unsupported value.

  [EPERM]   The caller does not have the appropriate privileges to set the
	    scheduling policy or parameters of the specified thread.

  [ESRCH]   The value specified by thread does not refer to an existing
	    thread.


ERRORS
  None



RELATED INFORMATION
  Functions: pthread_attr_setschedparam(3), pthread_attr_setschedpolicy(3),
  pthread_create(3), pthread_self(3), sched_yield(3)

  Manuals: Guide to DECthreads and Programmer's Guide

Index for Section 3

Alphabetical listing for P

Top of page